Pioneer 1074 Wont start

[mixemlewis]

Hey guys, I have a pioneer 1074 that I rebuilt the carb on as it was all original and the gaskets were pretty worn. It now wont start. Checked the plug and it was deff getting the gas. Wondering what might be going on here

 

[Old2stroke]

Did it start before you rebuilt the carb? The engine needs fuel, ignition and compression to start, so you have to figure out which is missing. Sounds like you found the plug to be wet with fuel so you could check that off for now, but be sure the engine isn't just flooded. Clean and dry the plug off (or better yet, use a known good plug), then place the plug lead back on, and with the ignition switch on, hold the plug threads against the cylinder, pull the engine over briskly and check for spark. If it has spark, stick the plug back in the engine and try to start it with NO choke and the throttle held wide open. If it doesn't start, pull the plug and if it is soaking wet again, the engine is flooded. A simple test for compression is to try to lift the saw off the floor with the starter handle. If the saw stays on the floor and the rope pulls out, you have a low compression issue. Try some of these and let us know how you make out.

 

[mixemlewis]

Thanks a lot man I'll try those mentioned things and get back

 

[mixemlewis]

And No it would not start at all before hand

 

[mixemlewis]

Checked over again. Brand new plug, good compression and no plugged lines. Anything else to check? Getting fuel in the carb.

 

[dsell]

If you have spark, compression, fuel, and timing is correct (no sheared flywheel key), then you are flooding it. Probably the inlet needle is not sealing correctly or not set correctly. There is also the possibility that you put incorrect circuit gaskets in, or have the gaskets in the wrong order. It's easy to do.

 

[mixemlewis]

Ok. Will recheck all that. How can I get it to the point that it will flash right up on the first pull?

 

[dsell]

Ok. Will recheck all that. How can I get it to the point that it will flash right up on the first pull?

It will eventually. We forgot one other thing, you could have air leaks. Air leaks such as crank seals, carb and intake gaskets, crankcase gaskets, cylinder gaskets, decompression valve if it has one, spark plug. Since you say the cylinder is getting fuel, I wouldn't worry too much about air leaks yet.

 

[mixemlewis]

Ok. There is a screw in the center of the exhaust that goes right into the chamber. I think thats the decomp? It does have that easy arc thing. I checked all that and made sure she's tight. I am going to recheck the gaskets on the carb t/n as I just rebuilt the carb and replaced the feed line. Do the fuel lines need to be bled?

 

[dsell]

Ok. There is a screw in the center of the exhaust that goes right into the chamber. I think thats the decomp? It does have that easy arc thing. I checked all that and made sure she's tight. I am going to recheck the gaskets on the carb t/n as I just rebuilt the carb and replaced the feed line. Do the fuel lines need to be bled?

No, the fuel lines will purge the air as you pull the rope if the fuel pump is working.

 

[dsell]

Did your rebuild the carb against a diagram?

 

[mixemlewis]

No diagram, just matched the originals against the new ones one by one.

 

[dsell]

No diagram, just matched the originals against the new ones one by one.

Ok, it didn't run before, so how do you know it was correct to begin with? Most manufacturers post the diagrams online. Yours maybe so old that it's hard to find.

 

[mixemlewis]

It showed signs of being factory installed. The gaskets were so worn and deteriorated that id say it has never been apart.

 

[Old2stroke]

You have tried a new plug, but did you actually verify that you had spark? It takes more spark energy to fire a plug under compression in the cylinder than in free air, so a better test when checking for spark is to open the plug gap up to about .050". If it will fire that gap outside the engine, it will probably fire a regular gap (.030") inside the engine. That saw has the old points type ignition, and it's common in a saw that old to have to clean the points, and probably replace the capacitor.
Not positive, but I thought that saw had a decomp valve that was levered open by the recoil starter mechanism. Worth checking in case it's sticking open.
You have to be sure the engine isn't just flooded. When a 2-stroke gets flooded, you can't just hold the throttle open and hope it will start if you pull it a zillion times because the gas part of the fuel will evaporate but the plug will be left coated with a conductive oily residue from the oil in the fuel. You have to remove the plug, wash it in straight gas, blow it dry, then install it and try to start again. NO choke and open throttle. Repeat this until the engine either fires or the plug stays dry, then you will know if it was flooded.

 

[mixemlewis]

Ok, when you say no choke, do you mean leave it fully closed? Where in the recoil would I find that valve? I had that apart when doing the restore to replace the cord and I didnt see anything that resembled a valve.

 

[mixemlewis]

No such luck. She is deff flooding. Did what you mentioned, and the plug was wet and there was prob about 2 teaspoons of gas in the chamber. What should I check?

 

[dsell]

Like 2stroke said, you have to make sure you have spark. There are testers available. The dangerous way to test is remove the plug from the cylinder, plug it back in the wire, lay it against conductive metal on the engine, pull the rope and the plug should spark bright blue. Keep in mind you are making sparks while the engine is emitting gas, so it would be wise to take it outside to do this test. If it's red or weak, you need to clean the points. This will not test the plug under pressure, so it doesn't thoroughly test the system.

Have you measured the compression? Every saw is different, but they get hard to start under 120psi. 90psi will still "feel" like your have compression, but will probably never start.

If you have compression, spark, then it's back to what I said about the carburetor. The inlet needle is stuck, not seating, incorrectly adjusted, or the mixture screws are incorrectly adjusted.

 

[mixemlewis]

Dont have a compression guage. I did a test that one person told me. holding the saw by the cord and seeing if it drops to the floor. (it did not) Plug does spark blue and is brand new. Dont those needles only seat one way? I installed a new one when I did the rebuild. What is the normal amount of fuel that I should be seeing getting to the chamber?

 

[dsell]

Dont have a compression guage. I did a test that one person told me. holding the saw by the cord and seeing if it drops to the floor. (it did not) Plug does spark blue and is brand new. Dont those needles only seat one way? I installed a new one when I did the rebuild. What is the normal amount of fuel that I should be seeing getting to the chamber?

You shouldn't see any fuel pooled. "Dont those needles only seat one way?" I assume you are referring to the inlet needle. There is a metering lever that raises and lowers the inlet needle to allow more fuel in the metering chamber. That metering lever must be adjusted correctly. If the lever is too high, the needle will never close or cause flooding. If the meter is too low, the saw will be lean or not run. The only way you know that adjustment is with the repair document from the manufacturer. The diaphragm pushes against this lever to open the needle with each impulse from the cylinder.

What is the brand and numbers on the carb?